For the past few days I've been fossicking around for material for a lecture on the songs and music of the Great War (for which the Mudcat and the DT have been invaluable thanks be to y'all), and I came across a remarkable site.
I haven't spotted it mentioned in the forum before, so apologies if it's well-known, but it's an astonishing collection of sheet music held at the Mississippi State University Library, the Charles H.Templeton collection.
In the words of the site:
For some forty years, Starkville, Mississippi, businessman Charles  Templeton collected a wide range of music memorabilia.
Included among his treasures is a collection of some 22,000 pieces of sheet music from late nineteenth and early twentieth century America.
The sheet music illustrates a broad spectra of music genres, from the ragtime of Scott Joplin to the dixieland of W. C. Handy to the smooth ballads of Irving Berlin to the stirring patriotic anthems of John Phillips Sousa and George M. Cohan to the early roots of big band sounds.
In addition to detailing the evolution of American music, these songs bring to life the times, trials, tribulations, and triumphs of a still young nation emerging from the shadows of Civil War and soaring with optimism.
The music also reflects the fabric of a society struggling to come to terms with an increasingly multi-cultural heritage, its role as an emerging world power, and its vulnerability to erratic economic and political forces. The music is, in fact, a snapshot of a dynamic generation.
The Charles H. Templeton Ragtime Sheet Music Collection is being digitized in an effort to preserve the collection as well as make it more accessible to researchers. Since a project of this magnitude can take months to complete, the MSU Library Administration made the decision to develop the Charles H. Templeton Ragtime Sheet Music Collection web site to give MSU Faculty, Students, Starkville townspeople and researchers a glimpse into the contents of this fabulous collection. The contents of this web site will be enhanced over the coming months.